Energy conservation and emission reduction have become a main design direction in the development of the automotive industry nowadays, and design requirements of full vehicles on transmissions are increasingly strict. Therefore, dual-clutch automatic transmissions having high efficiency, high comfort and high speed ratio ranges gradually become a development trend. The structure of power train and the arrangement of parking ratchet wheels in the dual-clutch automatic transmissions are important parts of the entire transmissions, and are also primary conditions in subsequent mechanical hardware design and software design. As such, the requirements of the dual-clutch automatic transmissions on power train and the arrangement of the parking ratchet wheels are higher and higher.
With regard to the power train, in order to obtain better dynamic performance and economical efficiency, a wider speed ratio range and a more reasonable speed ratio distribution have become an important development direction of the transmissions. Although great progress has been made in the shafting design of a lot of dual-clutch automatic transmissions, some defects caused by non-overall consideration still exist, resulting in shortcomings on the aspects of structure compactness, transmission performance and working stability.